New Medicines | WJEC GCSE Biology: Combined Science Revision Notes 2018

Discovering & Developing New Medicines

Traditionally, drugs were extracted from plants and microorganisms
New drugs are being developed all the time by scientists at universities and drug companies around the world
All new drugs need to be tested and trialled before they can be used in patients. They are tested for:
- Toxicity – does it have harmful side effects?
- Efficacy – does the drug work?
- Dose – what dose is the lowest that can be used and still have an effect?

Preclinical testing
- The drug is tested on cells and tissues in the lab
- Computer models may also be used to simulate the metabolic pathways that may be taken by the drug
- Efficacy and toxicity are tested at this stage
Whole organism testing
- The drug is tested on animals to see the effect in a whole organism – all new medicines in the UK have to have tests on two different animals by law
- Efficacy, toxicity and dosage are tested at this stage
Clinical trials
- The drug is tested on human volunteers first, generally with a very low dose then increased. This is to make sure it is safe in a body that is working normally
- The next stage is to test on patients with the condition
  - The patients are often split into two groups; one given the drug the other given a placebo. This is called a double-blind study – neither the doctor nor the patient knows if the patient is getting the placebo or the active drug
- Once the drug is found to be safe then the lowest effective dose is tested at this stage

Drugs testing protocol

Be sure you know the definitions of keywords associated with the development of new drugs:

Blind trial - the patient does not know whether they are taking the drug being tested or a placebo
Double-blind trial - both the doctors and the patients do not know whether they are taking the drug being tested or a placebo (only the drug company will know)
- Blind and double-blind trials prevent bias in any results obtained
Placebo - a substance administered like the drug but does not have any effects on the body
Placebo effect - the patient/volunteer expects treatment to work and so 'feels better', even though they have not been given the drug (they have been given the placebo)

Risks of developing new drugs include side effects that present themselves in patients even after extensive testing has been carried out
- Often new side effects and harmful effects do not show up until lots of people are taking the new drug

Drug testing allows large-scale data collection to further develop new and improved drugs whilst minimising the risks
Overall, the benefits of developing new drugs often outweigh the risks

Testing drugs on live animals raises some ethical issues
It can be considered cruel to test drugs on animals as it can cause pain and distress to the animals
- Animals are often kept in small unnatural laboratory cages
- The drugs may cause harmful effects to the animals being tested
Some people think it is necessary to test on live animals to ensure the safety of humans
Some people think it is ok to test on animals as laboratories adhere to strict protocols ensuring animals' basic needs are met and looked after
New technologies have been and continue to be developed that give alternatives to testing on animals
- Using computer models is one example of how a drug can be tested without the need for animal testing
- It is thought that new technologies could supersede the need for animal testing; this would be beneficial as testing on an animal is not a foolproof way to ensure the safety of a new drug on humans, as animals will metabolise medications differently to humans